2 files changed, 67 insertions, 52 deletions

diff --git a/arch/um/sys-i386/ldt.c b/arch/um/sys-i386/ldt.c
index dc755b0b9db8..bd3c34aa52e5 100644
--- a/arch/um/sys-i386/ldt.c
+++ b/arch/um/sys-i386/ldt.c
@@ -4,96 +4,106 @@
  */
 
 #include "linux/config.h"
+#include "linux/sched.h"
 #include "linux/slab.h"
+#include "linux/types.h"
 #include "asm/uaccess.h"
 #include "asm/ptrace.h"
+#include "asm/smp.h"
+#include "asm/ldt.h"
 #include "choose-mode.h"
 #include "kern.h"
+#include "mode_kern.h"
 
 #ifdef CONFIG_MODE_TT
-extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
 
-/* XXX this needs copy_to_user and copy_from_user */
+extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
 
-int sys_modify_ldt_tt(int func, void __user *ptr, unsigned long bytecount)
+static int do_modify_ldt_tt(int func, void *ptr, unsigned long bytecount)
 {
-        if (!access_ok(VERIFY_READ, ptr, bytecount))
-                return -EFAULT;
-
         return modify_ldt(func, ptr, bytecount);
 }
+
 #endif
 
 #ifdef CONFIG_MODE_SKAS
-extern int userspace_pid[];
 
+#include "skas.h"
 #include "skas_ptrace.h"
 
-int sys_modify_ldt_skas(int func, void __user *ptr, unsigned long bytecount)
+static int do_modify_ldt_skas(int func, void *ptr, unsigned long bytecount)
 {
         struct ptrace_ldt ldt;
-        void *buf;
-        int res, n;
+        u32 cpu;
+        int res;
 
-        buf = kmalloc(bytecount, GFP_KERNEL);
-        if(buf == NULL)
-                return(-ENOMEM);
+        ldt = ((struct ptrace_ldt) { .func      = func,
+                                     .ptr       = ptr,
+                                     .bytecount = bytecount });
 
-        res = 0;
+        cpu = get_cpu();
+        res = ptrace(PTRACE_LDT, userspace_pid[cpu], 0, (unsigned long) &ldt);
+        put_cpu();
+
+        return res;
+}
+#endif
+
+int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+{
+        struct user_desc info;
+        int res = 0;
+        void *buf = NULL;
+        void *p = NULL; /* What we pass to host. */
 
         switch(func){
         case 1:
-        case 0x11:
-                res = copy_from_user(buf, ptr, bytecount);
-                break;
-        }
+        case 0x11: /* write_ldt */
+                /* Do this check now to avoid overflows. */
+                if (bytecount != sizeof(struct user_desc)) {
+                        res = -EINVAL;
+                        goto out;
+                }
+
+                if(copy_from_user(&info, ptr, sizeof(info))) {
+                        res = -EFAULT;
+                        goto out;
+                }
 
-        if(res != 0){
-                res = -EFAULT;
+                p = &info;
+                break;
+        case 0:
+        case 2: /* read_ldt */
+
+                /* The use of info avoids kmalloc on the write case, not on the
+                 * read one. */
+                buf = kmalloc(bytecount, GFP_KERNEL);
+                if (!buf) {
+                        res = -ENOMEM;
+                        goto out;
+                }
+                p = buf;
+        default:
+                res = -ENOSYS;
                 goto out;
         }
 
-        ldt = ((struct ptrace_ldt) { .func      = func,
-                                     .ptr       = buf,
-                                     .bytecount = bytecount });
-#warning Need to look up userspace_pid by cpu
-        res = ptrace(PTRACE_LDT, userspace_pid[0], 0, (unsigned long) &ldt);
+        res = CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func,
+                                p, bytecount);
         if(res < 0)
                 goto out;
 
         switch(func){
         case 0:
         case 2:
-                n = res;
-                res = copy_to_user(ptr, buf, n);
-                if(res != 0)
+                /* Modify_ldt was for reading and returned the number of read
+                 * bytes.*/
+                if(copy_to_user(ptr, p, res))
                         res = -EFAULT;
-                else 
-                        res = n;
                 break;
         }
 
- out:
+out:
         kfree(buf);
-        return(res);
-}
-#endif
-
-int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
-{
-        return(CHOOSE_MODE_PROC(sys_modify_ldt_tt, sys_modify_ldt_skas, func, 
-                                ptr, bytecount));
+        return res;
 }
-
-
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
diff --git a/include/asm-um/ldt.h b/include/asm-um/ldt.h
new file mode 100644
index 000000000000..e908439d338a
--- /dev/null
+++ b/include/asm-um/ldt.h
@@ -0,0 +1,5 @@
+#ifndef __UM_LDT_H
+#define __UM_LDT_H
+
+#include "asm/arch/ldt.h"
+#endif